Inductively heated godet

ABSTRACT

A godet assembly in which a rotated, inductively heated cylindrical godet shell is provided on its inner wall with radially recessed openings from which there extends an axially recessed opening, preferably triangular in a longitudinal section, a non-magnetic material of high electrical conductivity such as copper being advantageously filled into these recessed openings in close adherent contact with the wall surfaces of the openings, such that the openings and preferably with the embedded non-magnetic material are arranged radially and axially to maintain a uniform temperature on the outer circumferential surface of the shell.

United States Patent 1 Bauer et al.

[54] INDUCTIYELY HEATED GODET [72] Inventors: Karl Bauer; GerhardMartens;l-lerbert Schiminski, all of Remscheid, 7 Germany v [73]Assignee: Barmag Barmer Maschinenlabrik Aktiengesellschaft, Wuppertal,Germany 22 Filed: Sept. 17, 1970 211 Appl.No.: 73,004

[451 Oct. 31, 1972 FOREIGN PATENTS OR APPLICATIONS 1,172,586 12/1969Great Britain ..2l9/469 Primary Examiner-J V. Truhe AssistantExaminer-Hugh D. Jaeger Attorney-Johnston, Root, OKeeffe, Keil, Thompson& Shurtleff [57] ABSTRACT A godet assembly in which a rotated,inductively heated cylindrical godet shell is provided on its inner wallwith radially recessed openings from which there extends an axiallyrecessed opening, preferably triangular in a longitudinal section, anon-magnetic material of high electrical conductivity such as copperbeing 1 advantageously filled into these recessed openings in closeadherent contact with the wall surfaces of the openings, such that. theopenings and preferably with the embedded non-magnetic material arearranged radially and axially to maintain a uniform temperature on theoutercircumferential surface of the shell.

9 Claims, 2 Drawing Figures PATENTEnncr a1 1912 3. 701. 873

GERHARD MERTENS HERBERT SCHIMINSKI ATT'YS- 1 INDUCTIVELY HEATED comerThe invention generally relates to an inductively heated godetfortextile machines or the like, e. g., for

the heat treatment of filaments, threads, yarns, ribbons, foils orsimilar. materials running continuously in contact with a rotatablymounted shell of the godet, this shell surrounding a stationary axialcore'of a ferromagnetic material which is wound by a coil connected witha source of alternating current.

lnductively-heatable godets of this type are generally known. Forexample, US. Pat. No. 3,412,228 describes a heating drum which consistsof a freely rotatable hollow roller which is mounted for rotation at theend of a driven shaft. In the interior of the hollow roller there isfixedly arranged a core of laminated iron plates, which concentricallysurrounds the drive shaft and which is arranged on a machine frame orsupport in such a way that it does not participate in the rotation ofthehollow roller. The corecarries one or more coils consisting of numerouswindings whose connecting ends orelectrical lead wires are directedoutwardly and connected with an alternating current source. The coilforms the primary side of atransformenwhose secondary side is the hollowroller itself. When the coil is traversed by an alternating'current,then there is generated in the core a magnetic field which enters thetwo face plates of the hollow roller and from there is conducted intothe cylindrical shell of the roller. The magnetic flux in the shellgenerates an electrical potential standing perpendicular to the lines offorce, which in turn induces a current in the shell or roller wall in aplane normalto the axis of the roller, i.e. circumferentially thereof.In consequence of the ohmic resistance of the shell or roller wall, itis heated by this so-called short-circuit current flowing therethr'ough.Eddy currents caused by the alternating magnetic flux alsocontribute tothe heating of the shell. I t The described inductive heatingarrangement would be suitable for generating a substantially uniformtemperature over the entire-length of theshell circumference if the heatrequirement of this shell were equally great at all points. However,thisv is not the case, since more heat'is led off at the terminal endsof the shell than in its middle portion. As a consequence, a strongtemperature drop takes place at the two ends of the shell, for examplein an amount of up to 30C., according to existing operating conditions.

In order to equalize the temperature profile, i.e. along the length ofthe roller, it is known from the above-noted patent U.S. Pat. No.3,412,228 to arrange on the interior of the shell a number of rings ofelectrically well-conducting and non-magnetizable material, these ringshaving a thickness which is adapted to the heat requirement of theparticular location on the roller wall. The evening of the temperatureprofile through such rings is brought about due to the fact that therings have a considerably lower electrical resistance than the shell orroller wall, usually consisting of steel, so that with equal voltageapplied thereto, a considerably higher current flows in thecircumferential direction. This current results in a stronger localheatdevelopment, whereby one can compensate for the differing amounts ofheat being lost over the length of the shell.

Measurements which we have made on godets constructed in this mannerhave shown that actually the 2 temperature profile still presentsappreciable deviations from the desired linear distribution, which isdue in part to. the fact that because of the narrow spacerelations'within the interior of the shell, there cannot be positionedan arbitrarily large amount of highly-conductive material at thenecessary locations along the inner wall of the godet shell.Furthermore, we have also found that in the known hollow roller device,the effect of the highly-conductive layer also remains quite limitedthrough the fact that the heat transmission between the rings or annularlayers'and the godet shell is not equally good at all points of thecircumference.

. Difficulties are presented in installing such rings, which of thegodet and its terminal ends is as small as possible.

Other objects and advantages of the invention will become more apparentupon consideration of the following detailed specification. v i

It has now been found, in accordance with the invention, that in aninductively-heatable godet assembly of the general type describedherein, the temperature distribution over the length of the godet shellcan be substantially improved by one especially advantageous embodimentin which a plurality of annular rings composed of a non-inagnetizablematerial of high electrical conductivity are embedded in the inner wallof the cylindrical shell in a radially recessed portion thereofextending around the entire circumference of the'shell, at least one ofthe embedded annular rings being profiled to profile an axial projectiontherefrom of smaller radial thickness extending toward the adjacentterminal end of the shell, this projection being inthe form of anannular collar-like extension of the annular ring and also beingembedded in a correspondingly axially recessed extension of the radiallyrecessed portionv of the shell, each of such rings being so disposedaxially and radially of the shell as to maintain the outercircumferential surface of the shell at a substantially uniformtemperature while being heated. The collarlike extensions of the annularrings adjacent the terminal ends of the shell preferably extend into theterminally heated zones of the shell.

With this particular construction, i.e. with the embedded annularcollar-like projections being located in the terminal ends or terminalheating zones of the embodiment of the invention'that the collar-likepro jections of the annular rings be provided with a triangularcross-section, as taken on a longitudinal section through the axis ofrotation of the shell, the radial thickness of each projectionreducinggradually up to its apex located in the terminal zone of one endof the shell. This provides a certain constriction of the inductivelyheated shell such that there arises a uniform temperature profile overthe entire length of the godet.

The individual annular rings with their collar-like projections areadvantageously formed in the corresponding recesses by the powder sprayprocess, which is well known, or they may also be formed by sinteringand, in either of these processes, solidly joined with the godet shell.With use of these known powdermetallurgical methods, it is not necessaryto first produce the rings outside the godet shell and theninstall themin corresponding recesses, but instead the rings with their projectionsare constructed directly in the recesses of the godet shell and aresimultaneously joined most intimately with the shell. The recesses inthe shell can be turned out in a likewise conventional manner accordingto a predetermined shape and configuration. Through these measures, itis assured that the heat transfer. from the embedded rings to the godetshell is consistent throughout the length and circumference of theshell.

The invention is explained in greater detail with reference to theaccompanying drawing in which:

. FIG. 1 is a partly schematic and longitudinal sectional view throughthe axis of rotation of a preferred embodiment of the godet assemblyaccording to the invention; and

FIG. 2 is a graphical representation of various temperature profilesachieved with different shell constructions of the godet. 1

Referring first to FIG. 1, the godet 1 consists essentially of thecylindrical shell 2 which is freely rotatably magnetizable material,such as laminated iron plates.

The core 7 has a U-shaped cross-section which is constructed in theillustrated embodiment such that the two radial legs or shanks 8 and 9are of equal length and terminate in close proximity to the inner wallof the godet shell 2. The core 7, with the aid of a mounting bracket 10,is rigidly joined through the intermediate support 4a to the machineframe 4, so that it does not participate in the rotation of the godetshell 2 and its drive shaft 3. The core 7 further carries a coil 11consisting of several windings, whose terminal ends or lead wires 12 and13 are directed out of the godet through a conduit 14 and connected witha source of alternating current which is shown schematically.

For the evening of the temperature profile, i.e. to provide a uniformtemperature distribution over the length of the godet shell inaccordance with the invention, two annular or circular rings 15 and 16are embedded in the wall of the godet shell 2. These annular rings bear,in the heating zone of at least one and preferably both terminal ends 17and 18 of the godet shell, the axially recessed collar-like projections19 which are composed of the same material as the rings 15 and 16 andwhich extend around the entire circumference of the shell 2. Thesecollar-like projections preferably have a triangular cross-section, asrepresented in FIG. 1, and are advanced so far into the terminal ends orzones 17 and 18 of the godet shell 2 as well as decreasing in thicknessthat the desired uniform temperature profile is closely approximatedover the entire length of the heated godet.

It is particularly desirable to arrange these two annular rings 15 and16 adjacent the terminal ends of the godet shell 2 such that at leasttheir triangular projections partially overlap the radial positions ofthe core legs 8 and 9, respectively, while still permitting a flow ofthe magnetic flux or lines of force directly over a small air gap in thewall of the godet shell 2. Thus, by sloping these triangular projectionsoutwardly toward the ends of the godet and away from the facing ends ofthe core legs 8 and 9, the magnetic flux is directed in a constrictedpath towards the ends of the godet shell and then sharply around theapices of the projections along the combined outer circumferentialsurfaces of the rings and their projections in a similarly restrictedconcentric path.

The particular shape or configuration of the core 7 as represented inFIG. 1 has thus proved to provide especially favorable results incombination with profiled rings 15 and 16. This core has two equallyextended legs 8 and 9 providing an outside dimension 20 whichcorresponds, at least approximately to the length of the heatable godetshell 2. The axial and radial arrangement of the collar-like projections19 of rings 15 and 16, whether of triangular cross-section or some othershape, should then extend into the range or in the close vicinity of themaximal outside dimension 20 of the core legs. In this manner, themagnetic flux is compelled to permeate the godet shell 2 up to-the endsof its effective length'and to generate electrical currents by inductionin this location, resulting in a short-circuit heating of the godetshell in its terminal zones. The illustrated U-shaped configuration ofthe core furthermore has the purpose of assuring that no mechanicalforces of any kind are transmitted to the bearings 21 or the shaft 3,which would be the case if, for example, there were to be used in placeof the illustrated core 7, an elongated core such as is shown in U.S.Pat. No. 3,412,228. Similarly, mechanical forces would be transmitted tothe shaft 3 and thereby the bearings 21 if the shanks had differentlengths, in which case the longer shank would necessarily be positionedadjacent a projection or fitted into a recess of the godet shell.

By experimentatiomit was surprisingly ascertained that in many instancesit is even possible to completely omit the inlaid or embedded annularrings 15 and 16 with their projections 19 and still achieve a highlyimproved and quite adequate evening or linearization of the temperaturealong the length of the godet shell. In other words, in place of theembedded profiled annular rings, it is feasible to merely providerecesses in the inner wall. of the godet shell of the correspondingshape or configuration. This means that the inner wall contains at leasttwo radially recessed openings extending ally recessed opening alsoextending around the entire circumference of the shell while protrudingfrom one side of one and preferably both of the radiallyrecessedopenings toward the adjacent terminal end or zone of the godet shell.

With a triangular or similar cross-section of this concentric axiallyrecessed opening, the "radial gap thereacross reduces gradually frornthe radially recessed opening outwardly to an apex located in theterminal zone of the shell. Again, this gap of reducing dimensionspreferably-overlaps the radially positioned legs of the wound core so asto provide a sharp constriction in the thickness'of the godet shellatits terminallyheated ends. The corresponding constriction ordisplacement of the pathsof the magnetic flux through the shell at oneand preferably both ends is in itself sufficient to generate a largeramount of heatwhere it is most required so as to bring about a verysubstantial linearization of the temperature profile along the length ofthe shell.

I Although this (mission of the embedded electricallyconductive materialso as to merely provide corresponding radially and axially recessedopenings does not give the best results, such an alternative embodimentof the invention is obviously less expensive and often providessatisfactory results. Moreover, the recessed openings alone offer ameans of first determining the optimum configuration for a'subsequentinlay of the highly conductive material, or if the results obtained withonly-these openings proves to be sufficient for a given case, theresulting godetshell can be utilized without any further construction.It is, of course, also feasible to fill such useful recesses with asuitable non-magnetic and electrically non-conducting insulatingmaterial. a l

The effect achieved with the illustrated embodiments of the godet shell:with the required recesses or embedded rings can be readily observed inFIG. 2. In this graph, the horizontal axis represents the length of thegodet shell in centimeters. On the vertical axis, there is plotted thesurface temperature in degrees Centigrade of the heated godet. Curve 1shows the temperature gradient ordinarily achieved over the length ofthe godet, i.e. when no turned recesses are present in the godet shellso that it has a uniform wall thickness. In this case, temperaturedifferences of 20 and more appear between the ends of the godet and itsmidpoint. If, according to the invention, suitably turned or formedrecesses are arranged in the interior of the godet shell as illustratedin FIG. 1 without any emcopper alloys, such as bronze or brass. It isalso possible to use other non-magnetizable but goodelectricallyconducting materials, such as aluminum or the like. Incarrying out these experiments for the production and use of such godetsaccording to the invention, it has been found that the inlays orembedded rings are effective in a double respect. In the f rst place, asa consequence of the better electrical conductivity of these rings comprfid to the godet shell, there is generated an additional amount of heatwithin the rings'which is given offby direct heat conduction to thetightly adherent shell. In the second place, however, there arises stillanother effect, namely that the magnetic flux is dis placed by thenon-magnetizable inlays and with a suitable placement and configurationof these inlays flows into those parts of the godet shell in which theadditional amount of heat is needed. In this manner, these parts arefully traversedby the flux and in a'somewhat bedded material, then it isalready possible .to reduce restricted path, so that anincreased currentis even generated by induction in these parts and consequently therearises an additional supply of heat. This double effect of the inlaysaccording to the invention can be utilized especially well if the core;in a generally known construction, exhibits a. U-shaped cross-section,in

length of the godet shell. 7

The godet shells of theinvention are relatively easily.

constructed by using conventional powder-metallurgical techniques inorder to provide the embedded rings of. copper or the like. By using theoptimumconfiguration of these inlays, the godets of the invention permita much more uniform heat treatment of transported threads, yarns andsimilar materials.

The invention is hereby claimed as follows;

1. In a godet assembly having a rotatable, cylindrical,inductively-heatable shell enclosing a stationary core of aferromagnetic material wound with an induction coil with means to supplyan alternating current to said coil for heating said shell, theimprovement which comprises: I a i a core having a U-shapedcross-section defined by a base member extending along the axis of thegodet and oppositely disposed radial legs extending outwardlytoward theterminal zone at either end of said shell; and

a plurality of annular rings composed of a non-magnetizable material ofhigh electrical conductivity embedded in the inner wall of saidcylindrical shell in radially recessed portions thereof extending aroundthe entire circumference of the shell, ineluding a pair of such ringsadjacent said terminal zones, at least one of said pair of annular ringsbeing profiled to provide an axial projection therefrom of smallerradial thickness extending into the adjacent terminal zone of said shellwith the terminal zone being disposed radially oppositely of itscorresponding core leg, said projection also being embedded in acorrespondingly axially recessed extension of said radially recessedportion of said shell, each of said annular rings being the projectionsof each annular ring have a substantially triangular cross-section astaken on a section longitudinally of the shell, the radial thickness ofthe projection reducing gradually up to an apex located in said Iterminal zone at either end of said shell.

5. A godet assembly as claimed in claim 1 wherein said annular rings arein intimate adherent contact with the inner walls of said radially andaxially recessed portions of said shell.

' 6. In a godet assembly having a rotatable, cylindrical,inductively-heatable shell enclosing a stationary core of aferromagnetic material wound with an induction coil with means to supplyan alternating current to said coil for heating said shell, theimprovement which comprises:

a core having a U-shaped cross-section defined by a base memberextending along the axis of the godet and oppositely disposed radiallegs extending outwardly toward the terminal zone at either end of saidshell; and

a shell whose inner wall contains a plurality of radiallyrecessedopenings extending around the entire circumference of the shell,including a pair of such recessed openings adjacent said terminal zones,and an axially recessed opening of smaller radial dimension.extendingfrom one side of at least one of said pair of radially recessedopenings into the adjacent terminal zone of said shellwith the terminalzone being disposed radially oppositely of its corresponding core leg,each of said recessed openings being so disposed axially and radially ofthe shell as to maintain the outer circumferential surface of said shellat a substantially uniform temperature while being heated.

7. A godet assembly as claimed in claim 6, wherein the axially recessedopenings extending from each radially recessed opening have asubstantially triangular cross-section as taken on a sectionlongitudinally of the shell, the radial gap across said axially recessedopening reducing gradually from said radially recessed opening outwardlyto an apex located in said terminal zone at either end of said shell.

8. A godet assembly as claimed in claim 1 wherein said non-magnetizablematerial is a metal integrally formed and embedded in said radiallyrecessed portion and said axially recessed extension of said shell bythe powder spray process.

9. A godet assembly as claimed in claim 1 wherein said non-magnetizablematerial is a metal integrally formed and embedded in said radiallyrecessed portion and said axially recessed extension of said shell bythe sintering process.

1. In a godet assembly having a rotatable, cylindrical,inductively-heatable shell enclosing a stationary core of aferromagnetic material wound with an induction coil with means to supplyan alternating current to said coil for heating said shell, theimprovement which comprises: a core having a U-shaped cross-sectiondefined by a base member extending along the axis of the godet andoppositely disposed radial legs extending outwardly toward the terminalzone at either end of said shell; and a plurality of annular ringscomposed of a non-magnetizable material of high electrical conductivityembedded in the inner wall of said cylindrical shell in radiallyrecessed portions thereof extending around the entire circumference ofthe shell, including a pair of such rings adjacent said terminal zones,at least one of said pair of annular rings being profiled to provide anaxial projection therefrom of smaller radial thickness extending intothe adjacent terminal zone of said shell with the terminal zone beingdisposed radially oppositely of its corresponding core leg, saidprojection also being embedded in a correspondingly axially recessedextension of said radially recessed portion of said shell, each of saidannular rings being so disposed axially and radially of the shell as tomaintain the outer circumferential surface of said shell at asubstantially uniform temperature while being heated.
 2. A godetassembly as claimed in claim 1 wherein said annular rings are composedof a material selected from the class consisting of copper, copperalloys and aluminum.
 3. A godet assembly as claimed in claim 1 whereinsaid projection of said annular ring has a substantially triangularcross-section as taken on a section longitudinally of said shell, theradial thickness of the projection reducing gradually up to an apexlocated in the terminal zone of one end of said shell.
 4. A godetassembly as claimed in claim 1 wherein the projections of each annularring have a substantially triangular cross-section as taken on a sectionlongitudinally of the shell, the radial thickness of the projectionreducing gradually up to an apex located in said terminal zone at eitherend of said shell.
 5. A godet assembly as claimed in claim 1 whereinsaid annular rings are in intimate adherent contact with the inner wallsof said radially and axially recessed portions of said shell.
 6. In agodet assembly having a rotatable, cylindrical, inductively-heatableshell enclosing a stationary core of a ferromagnetic material wound withan induction coil with means to supply an alternating current to saidcoil for heating said shell, the improvement which comprises: a corehaving a U-shaped cross-section defined by a base member extending alongthe axis of the godet and oppositely disposed radial legs extendingoutwardly toward the terminal zone at either end of said shell; and ashell whose inner wall contains a plurality of radially recessedopenings extending around the entire circumference of the shell,including a pair of such recessed openings adjacent said terminal zones,and an axially recessed opening of smaller radial dimension extendingfrom one side of at least one of said pair of radially recessed openingsinto the adjacent terminal zone of said shell with the terminal zonebeing disposed radially oppositely of its corresponding core leg, eachof said recessed openings being so disposed axially and radially of theshell as to maintain the outer circumferential surface of said shell ata substantially uniform temperature while being heated.
 7. A godetassembly as claimed in claim 6, wherein the axially recessed openingsextending from each radialLy recessed opening have a substantiallytriangular cross-section as taken on a section longitudinally of theshell, the radial gap across said axially recessed opening reducinggradually from said radially recessed opening outwardly to an apexlocated in said terminal zone at either end of said shell.
 8. A godetassembly as claimed in claim 1 wherein said non-magnetizable material isa metal integrally formed and embedded in said radially recessed portionand said axially recessed extension of said shell by the powder sprayprocess.
 9. A godet assembly as claimed in claim 1 wherein saidnon-magnetizable material is a metal integrally formed and embedded insaid radially recessed portion and said axially recessed extension ofsaid shell by the sintering process.